Not too much activity around here, but let’s see if there’s any interest in this anyway. Prompted by facing a conundrum on paterous featuring 4 L’s (ILLEGALLY) I’m wondering what’s the biggest number of recurrences of the same letter you can have in a valid 9 letter word, for each letter. i.e. what’s the conundrum with the most A’s, most B’s etc. I've not spent too much time on it but here's a few ideas to kick things off

EQUIVOQUE wins Q I think. You can test it by putting something e.g. RRR into Lexplorer's Words Using and keep adding a letter until nothing appears with 9 letters (or change the length to 9). For instance, there's tons with 3 Rs so you try it with 4, and it only gives one nine (REFERRERS). I can't be bothered doing the rest of these.